Devices for magnetic control with permanent magnets

Abstract

A magnetic device comprising two permanent magnets, armature members forming with said magnets a closed magnetic circuit and an external air gap, and means for reversing the direction of magnetization of one of the magnets, whereby the flux is prevented to close along the magnetic circuit and caused to close through the air gap, or caused to close along the magnetic circuit, the flux in the air gap then being suppressed. The said means consist of two distinct coils wound about the magnets. One of the coils is energized for establishing the flux in the air gap, while the other coil is energized for suppressing the flux in the air gap.

I claim: 
     
       1. Magnetic device comprising at least one pair of permanent magnets, armature members forming with at least said one pair a closed magnetic circuit and also defining at least one air gap external to said circuit, said magnetic device comprising first and second coil and means energizing said coils for inverting the direction of magnetisation of one of the magnets of at least said one pair in such a manner as to modify the path of magnetic flux, by obliging it in one case to re-close itself by passing through at least said one air gap and in the other case, after inverting of the direction of magnetisation of one of the magnets, to re-close itself through the said magnet and partially or wholly suppressing the flux in the region of at least said one air gap, wherein only the first coil is energized for establishing the magnetic flux in the region of at least said one air gap, and only the second coil is energized for obtaining the partial or total suppression of the said flux, the direction of flow of current being constant in each of the coils. 
     
     
       2. Magnetic device in accordance with claim 1, wherein the said closed magnetic circuit has a symmetry of revolution and comprises first and second annular magnets, the first magnet being concentrically arranged about the second magnet, the first coil having first and second serially connected windings, the first winding being arranged outside the first magnet, the second winding being arranged inside the second magnet being disposed at each side of the magnets, and the second coil having a single winding arranged between the first and second magnets. 
     
     
       3. Magnetic device in accordance with claim 1, wherein said coils each have first and second terminals, said energizing means comprising a pulse generator having first and second outputs, first and second unidirectionally conducting electronic components respectively connecting the first terminal of the first and second coils to the said second output, and switching means connecting the said first output to the second terminals of the first and second coils. 
     
     
       4. Apparatus comprising a plurality of magnetic devices as claimed in claim 1, wherein said coils each have first and second terminals, said energizing means comprising a single pulse generator having first and second outputs, first and second unidirectionally conducting components respectively connecting in parallel the first terminal of each said first and second coils to the said second output, and switching means connecting in parallel to said first output to the second terminals of each said first and second coils.